accepts a 'type' argument.

In you case 'type = response' will give you the results in probabilities

(that it seems to be what you are looking for).

There also is an example on use of the 'type' argument at the end of the

page.

Stefano

-----Messaggio originale-----

Da: r-help-bounces at r-project.org

[mailto:r-help-bounces at r-project.org]Per conto di Troy S

Inviato: Friday, August 06, 2010 6:31 PM

A: Michael Bedward

Cc: r-help at r-project.org

Oggetto: Re: [R] Confidence Intervals for logistic regression

Michael,

Thanks for the reply. I believe Aline was sgiving me CI's on coefficients

as well.

So c(pred$fit + 1.96 * pred$se.fit, pred$fit - 1.96 *

pred$se.fit) gives me the CI on the logits if I understand correctly? Maybe

the help on predict.glm can be updated.

Thanks!

On 6 August 2010 01:46, Michael Bedward wrote:

Sorry about earlier reply - didn't read your email properly (obviously :)

You're suggestion was right, so as well as method for Aline below,

another way of doing the same thing is:

pred <- predict(y.glm, newdata= something, se.fit=TRUE)

ci <- matrix( c(pred$fit + 1.96 * pred$se.fit, pred$fit - 1.96 *

pred$se.fit), ncol=2 )

lines( something, plogis( ci[,1] ) )

lines( something, plogis( ci[,2] ) )

[[alternative HTML version deleted]]Sorry about earlier reply - didn't read your email properly (obviously :)

You're suggestion was right, so as well as method for Aline below,

another way of doing the same thing is:

pred <- predict(y.glm, newdata= something, se.fit=TRUE)

ci <- matrix( c(pred$fit + 1.96 * pred$se.fit, pred$fit - 1.96 *

pred$se.fit), ncol=2 )

lines( something, plogis( ci[,1] ) )

lines( something, plogis( ci[,2] ) )

On 6 August 2010 18:39, aline uwimana wrote:

Dear Troy,

use this commend, your will get IC95% and OR.

logistic.model <- glm(formula =y~ x1+x2, family = binomial)

summary(logistic.model)

sum.coef<-summary(logistic.model)$coef

est<-exp(sum.coef[,1])

upper.ci<-exp(sum.coef[,1]+1.96*sum.coef[,2])

lower.ci<-exp(sum.coef[,1]-1.96*sum.coef[,2])

cbind(est,upper.ci,lower.ci)

regards.

2010/8/6 Troy S <troysocks-twigs@yahoo.com>

______________________________________________

R-help at r-project.org mailing list

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PLEASE do read the posting guide

http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.

Dear Troy,

use this commend, your will get IC95% and OR.

logistic.model <- glm(formula =y~ x1+x2, family = binomial)

summary(logistic.model)

sum.coef<-summary(logistic.model)$coef

est<-exp(sum.coef[,1])

upper.ci<-exp(sum.coef[,1]+1.96*sum.coef[,2])

lower.ci<-exp(sum.coef[,1]-1.96*sum.coef[,2])

cbind(est,upper.ci,lower.ci)

regards.

2010/8/6 Troy S <troysocks-twigs@yahoo.com>

Dear UseRs,

I have fitted a logistic regression using glm and want a 95% confidence

interval on a response probability. Can I use

predict(model, newdata, se.fit=T)

Will fit +/- 1.96se give me a 95% of the logit? And then

exp(fit +/- 1.96se) / (exp(fit +/- 1.96se) +1) to get the probabilities?

Troy

[[alternative HTML version deleted]]

______________________________________________

R-help at r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide

http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.

[[alternative HTML version deleted]]I have fitted a logistic regression using glm and want a 95% confidence

interval on a response probability. Can I use

predict(model, newdata, se.fit=T)

Will fit +/- 1.96se give me a 95% of the logit? And then

exp(fit +/- 1.96se) / (exp(fit +/- 1.96se) +1) to get the probabilities?

Troy

[[alternative HTML version deleted]]

______________________________________________

R-help at r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide

http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.

______________________________________________

R-help at r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide

http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.

______________________________________________

R-help at r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.

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